Hi Porpoise, I'm Bill.
Your CPU uses the LGA1151 socket, so depending on your motherboard compatibility, you'd be able to upgrade to a Core i5 or i7 of the same socket. A couple of examples would be the i5 6600 or the i7 6700. Either of those would be a good upgrade for you.
If you want to upgrade any higher than those, you'd need to purchase a newer motherboard and RAM setup. But for now, those two options are good if you're looking to upgrade just your CPU.
Let me know if you need further information!